全文获取类型
收费全文 | 84390篇 |
免费 | 5418篇 |
国内免费 | 2678篇 |
专业分类
电工技术 | 4144篇 |
技术理论 | 9篇 |
综合类 | 4182篇 |
化学工业 | 14272篇 |
金属工艺 | 5012篇 |
机械仪表 | 5822篇 |
建筑科学 | 5270篇 |
矿业工程 | 2562篇 |
能源动力 | 2043篇 |
轻工业 | 4036篇 |
水利工程 | 1420篇 |
石油天然气 | 5803篇 |
武器工业 | 574篇 |
无线电 | 8747篇 |
一般工业技术 | 12677篇 |
冶金工业 | 5407篇 |
原子能技术 | 1052篇 |
自动化技术 | 9454篇 |
出版年
2024年 | 321篇 |
2023年 | 1262篇 |
2022年 | 2222篇 |
2021年 | 3137篇 |
2020年 | 2445篇 |
2019年 | 2223篇 |
2018年 | 3055篇 |
2017年 | 3316篇 |
2016年 | 3240篇 |
2015年 | 3259篇 |
2014年 | 4162篇 |
2013年 | 5197篇 |
2012年 | 5140篇 |
2011年 | 5524篇 |
2010年 | 4780篇 |
2009年 | 4829篇 |
2008年 | 4805篇 |
2007年 | 4462篇 |
2006年 | 4332篇 |
2005年 | 3541篇 |
2004年 | 2233篇 |
2003年 | 1968篇 |
2002年 | 1933篇 |
2001年 | 1727篇 |
2000年 | 2035篇 |
1999年 | 2180篇 |
1998年 | 1788篇 |
1997年 | 1549篇 |
1996年 | 1135篇 |
1995年 | 1001篇 |
1994年 | 810篇 |
1993年 | 585篇 |
1992年 | 481篇 |
1991年 | 342篇 |
1990年 | 302篇 |
1989年 | 209篇 |
1988年 | 188篇 |
1987年 | 114篇 |
1986年 | 81篇 |
1985年 | 73篇 |
1984年 | 64篇 |
1983年 | 46篇 |
1982年 | 47篇 |
1981年 | 30篇 |
1980年 | 35篇 |
1979年 | 23篇 |
1978年 | 24篇 |
1976年 | 20篇 |
1969年 | 23篇 |
1968年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
21.
An a posteriori (off-line) approach to the simultaneous detection and identification of quasi-periodic fragments in a numerical
sequence using their segments is analyzed. The solution of the problem is proposed for the case when the number of the desired
fragments is known. The following assumptions are made. (i) Each desired fragment of the numerical sequence coincides with
an element of the given alphabet of the reference sequences that have equal lengths (i.e., number of elements). (ii) Only
a segment (part) of the desired fragment can be processed; unprocessable parts of the fragment are interpreted as lost data.
(iii) The numbers of the elements in the sequence that correspond to the beginning of the desired fragment and the boundaries
of the segment in the fragment represent deterministic (rather than random) quantities; the boundaries of the segments are
different for different fragments; and the desired fragments are quasi-periodic in the sequence. (iv) Gaussian uncorrelated
noise impedes the observation of the sequence that contains quasi-periodic segments of the reference sequences. It is demonstrated
that the essence of the problem under study lies in the verification of a set of hypotheses on the mean value of a random
Gaussian vector (the power of this set exponentially increases with an increase in the dimension of the vector—the sequence
length). An effective a posteriori algorithm that provides for maximum-likelihood detection and identification is validated.
The estimates of the time and space complexity are related to the parameters of the problem. The results of the numerical
simulation are presented.
This work was supported by the Russian Foundation for Basic Research, project no. 03-01-00036 and 06-01-00058.
Aleksandr V. Kel’manov. Born April 25, 1952. Graduated from Izhevsk State Technical University in 1974. Received candidate’s degree in 1980 and
doctoral degree in 1994. Leading researcher of the Sobolev Institute of Mathematics, Siberian Division, Russian Academy of
Sciences. Scientific interests: mathematical methods for pattern recognition; discrete optimization; effective algorithms
for the analysis and recognition of random sequences; algorithms for the solution of applied problems; and methods and algorithms
for the processing, recognition, and synthesis of voice signals. Author of more than 120 papers.
Sergei A. Khamidullin. Born March 28, 1952. Graduated from Novosibirsk State University in 1974. Received candidate’s degree in 1997. Senior researcher
of the Sobolev Institute of Mathematics, Siberian Division, Russian Academy of Sciences. Scientific interests: mathematical
methods for pattern recognition; discrete optimization; effective algorithms for the analysis and recognition of random sequences;
algorithms for the solution of applied problems; and methods and algorithms for the processing, recognition, and synthesis
of voice signals. Author of more than 80 papers. 相似文献
22.
本文测量了某铀矿不同工种的56名矿工下矿井作业前的呼出气中的~(222)Rn浓度,并由此估算了他们体内的~(226)Ra 负荷量。按不同工种的人数加权,呼出气中的~(222)Rn 浓度平均值为34.1Bqm~(-3),体内~(226)Ra 负荷量的均值为1.95kBq。同时还对9名休息了2天的和2名离开井下作业3—4年的矿工以及12名来下过矿井的本矿工人呼出气中氡浓度进行了测量,由此估算出其体内~(226)Ra 负荷量的均值分别为1.11、0.94和0.17kBq。 相似文献
23.
S. O. Shiryaeva A. I. Grigor’ev V. A. Koromyslov A. S. Golovanov 《Technical Physics Letters》2002,28(1):41-43
A dispersion equation for the capillary oscillations of a charged drop of incompressible liquid possessing a finite electric
conductivity is derived with an allowance for the energy lost as a result of the electromagnetic wave emission. The magnitude
of the electromagnetic radiation losses of the oscillating drop linearly increases with the electric conductivity and the
surface mobility of charge carriers. 相似文献
24.
25.
狗经氡子体暴露后血、毛中~(210)Pb 和~(210)Po 含量的动态变化 总被引:1,自引:1,他引:0
本文叙述了实验狗经氡子体暴露后血、毛中~(210)Po、~(210)Pb 含量、~(210)po/~(210)Pb 比率及血中~(210)Po,~(210)Pb 排出的动态变化。 相似文献
26.
V. D. Belik R. V. Litvin M. S. Koval’chenko 《Powder Metallurgy and Metal Ceramics》2006,45(11-12):593-598
The influence exerted by electric-spark spraying on the kinetics of mass transfer and the physicomechanical properties of coatings is investigated. It is shown that electric-spark spraying is determined by the dynamic properties of the cathode jets, which depend on the electrical parameters of the spark discharge, the size of the interelectrode interval, and the physical properties of the coatings, which vary during spraying. 相似文献
27.
钒冶炼焙烧添加剂选择研究 总被引:1,自引:0,他引:1
对小型钒冶炼厂焙烧工艺所用添加剂进行改进的可能性进行了探讨,研究了几种常用添加剂的焙烧条件,分析比较了其性能,提出用NaCl-Na2CO3作焙烧添加剂替代NaCl可大幅度减少大气污染,提高冶钒转化率;且不改变工艺流程,无需设备投资,具有较好的经济效益和环境效益。 相似文献
28.
29.
30.
CAPP系统中工艺卡片生成过程的研究 总被引:10,自引:1,他引:9
以AutoCAD2 0 0 0为开发平台、VC + + 6 0为开发环境、ObjectARX2 0 0 0为开发工具、SQLServer为后台数据库 ,通过编写writeText、fillGykztb、fillGykjtb等自定义函数 ,生成工艺卡片 ,并实现工序内容在工艺卡片中的分页显示等功能。 相似文献